1. Field of the Invention
The present invention relates to filters, and more specifically to a method and apparatus for adjusting trans-conductance of a filter.
2. Related Art
A filter generally refers to a component which allows/passes a range of frequencies and rejects all other frequencies from an input signal. For example, a low pass filter allows all low frequencies below a cut off frequency (determined by filter components) and rejects all the high frequencies above cut off frequency.
Filters are often implemented within integrated circuits, and are thus characterized by trans-conductance. Trans-conductance generally provides a measure of the degree of conductivity of a filter and is represented as a reciprocal of resistance. Filter characteristics such as frequency response and amplification factor are determined by the trans-conductance value as is well known in the relevant arts.
One problem often encountered with filters is that the actual trans-conductance value is at variance with a desired value. The variance can be for reasons such as imperfections in manufacturing technologies and material, changes in operating conditions (e.g., surrounding temperature), etc. Accordingly, it is desirable to adjust the trans-conductance value of a filter during operation.